Esterified lignocellulosic materials such as acetylated wood can be desirable in some applications because of their greater dimensional stability than untreated lignocellulosic materials and because of other qualities. These advantages exist for both esterified solid wood materials such as acetylated boards and lumber and lignocellulosic materials of small particle size that are acetylated then used in composite materials. However, there remains a continuing need to improve the favorable properties of these materials. There is also a continuing need for esterification processes that are efficient and cost-effective. There is also a continuing need for esterification processes that provide a high degree of esterification and consistency in the degree of esterification in a given batch of material.